Switch structure for motor-driven tools



April 15, 1952 N. BRACKETT SWITCH STRUCTURE FOR MOTOR-DRIVEN TOOLS FiledJan. 26, 1950 IN V EN TOR.

Patented Apr. 15, 1952 UNITED STATES PATENT OFFICE SWITCH STRUCTURE FORMOTOR-DRIVEN TOOLS Ncwell Brackett, Bala-Cynwyd, Pa., assignor to CranePacking Company, Chicago, 111., a corporation of Illinois ApplicationJanuary 26, 1950, Serial No. 140,731

This invention relates to a control device for a hand-operated powertool such as a drill, tube expander, saw, or the like. For purposes ofillustration this invention will be described with reference to its useon a tube expanding device.

There has been devised an electrical motor driven power tool forperforming an expanding opepation upon tubes to cause them to seize witha fluid-tight seal in a drilled tube sheet. Such a power tool isdescribed for example in Dudley et a1. Patent No. 2,431,316, datedNovember 25, 1947. The tool is designed to be advanced into a tube, andthe amount of expansion of the tube is controlled by the length of timethe too-l operates against the tube and the closeness of the fit betweenthe tube and its tube sheet. The amount of expansion, however, iscritical. When the tube -is overexpanded, it becomes brittle and cannotwithstand the forces acting upon it while it is in normal operation. If,on the other hand, the tube is not expanded sufiiciently, a tight jointwill not be achieved and the tube will leak, thereby putting theassociated apparatus out of working order.

To control the amount of rolling accurately and consistently, anelectrical torque control has been devised, the control being insertedin the motor circuit in such a way that when the load on the motorreaches a predetermined value, the circuit through the motor isautomatically out off, thereby stopping the motor. The operation of thecontrol involves a manual operation of a switch at the start of eachrolling operation, in addition to the manually operated motor startinswitch.

In order to reduce the number of special motions required of theoperator, it is desirable that the manually operated switch for thecontrol be actuated automatically by some necessary movement of theoperator in the normal operation of the power tool.

The principal object of this invention is to provide a means forcontrolling a switch associated with a power tool, the switch beingconcealed and operated as an incident to the application of the normalpressure upon the power tool by the operator.

1 A more specific object of this invention is to provide a hinged handlefor a hand-openated power tool, the handle having a limited angle ofmovement, with a switch of the micro switch variety concealed in thehandle and operated by the oscillating motion of the handle about itshinge.

A feature of this invention is a construction of 3 Claims. (Cl. 172- 36)a hinged handle for a hand-operated power tool which permits the handleto be readily disassembled for inspection and repair.

These and other objects and features of this invention will becomeapparent from the following detailed description when taken togetherwith the accompanying drawings, in which Fig. l is a side elevation of ahand-operated power tool which incorporates a handle and a controlswitch made in accordance with this invention;

Fig. 2 is an enlarged view of the handle portion of the power tool ofFig. 1 with the cover removed to disclose the disposition of theswitches and their operating means; and

Fig. 3 is a section taken through the handle of Fig. 2 along line 3-3.

The hand-operated power tool is comprised primarily of a motor H], agear box I l the latter incorporating an automatically operatedreversing gear which is made effective whenever the tool is withdrawnfrom the work; a spindle l2 driven from the gear box I I, and a suitabletoolreceiving chuck [3 which is adapted to hold the expanding toolfrictionally for rotation with spindle I2. The frame 14 of the powertool is provided at its lower end with a hinge pin IS on which ismounted a U-shaped handle [6 which is gripped by the operator during thenormal operation of the power tool.

As shown in Fig. 2, the handle [6 is provided with a cavity I! in thelower leg of the U in which is disposed a toggle switch IS, a cavity I9in which is disposed a micro switch 20 and a cavity 2| in the upper legof the U in which is disposed a guide pin 22 secured to frame member 14.A spring 23 is compressed between handle it and frame [4 and normallytends to rotate handle l6 about hinge pin 15 in a clockwise direction asviewed in Fig. 2. An opening 24 is provided in the bottom of handle l6through which a cable 25 passes, saidcable having substantially fiveleads, two of 7 which, 26, 21, are connected to micro switch 20,

another two, 28, 29, are connected to toggle switch l8, and the fifth,30, is connected to the handle [and serves as a ground for the powertool. The leads 28, 29 are connected to a suitable source of power (notshown) and also to a control device (not shown) such as the aforesaidDudley device. Leads 26, 21 are likewise connected to the said controldevice. The electrical circuits which may be used are not material tothe operation of this invention and hence are not described in detailhere.

Micro switch 20 has an arm 3| extending outwardly beyond the upper endof switch 20 and terminating in a bracket 32 in which is pivotallymounted a roller 33. Guide pin 22 is aligned with roller 33 such thatupon pushing handle it toward the power tool, the end of pin 22 willcontact roller 33 and urge said roller to the right as viewed in Fig. 2..A movable contact operating pin 35 is interposedin the path of movementof arm 3|. As roller 33 is moved to the right, arm 3| is correspondinglymoved to the right also. Pin 34 will be contacted by arm SI and likewisewill be moved to the right to operate the contacts within switch 20 (notshown). Inasmuch as switch 20 may be any commercially available microswitch, the details of construction thereof are not described herein indetail.

Pin 22 is formed with a pair of lugs 35 (Fig. 3) which abut on stops 36formed in handle [6, thereby limiting clockwise rotation, as viewedinFig. 3, of handle it about its hinge pin i5.

counterclockwise rotation of the said handle is limited by contactbetween the end 36a of the handle and the frame member M. A slot 31 isformed in handle Hi, the slot being wide enough so that when hinge pinit is removed to free the lower end of the handle, said handle may berotated about pin 22 until lugs 35 are aligned with slot 3'1, whereuponhandle It may then be -withdrawn from the pin. This facilitates dismotorl0, and the tool is then moved to its work station. Pressure is appliedupon handle 16 by the operator to the left as viewed in Figs. 1 and 2 toadvance the tool into the tube to be rolled. The pressure overcomes theresistance of spring 23 and allows handle It to be rotated about itshinge pin 15 in a counterclockwise direction relative to frame memberHL- The counterclockwise rotation in turn causes pin 32 to strike roller33 thereby causing arm 3| to strike pin 34 and operate micro switch 20.condition will obtain as long as pressure is exerted upon handle it tooperate the tool in the tube. When the desired operation is completedatthe selected work station, the tool is withdrawn by pulling to the righton handle It. This, of course, reverses the thrust on the handle,causing the handle to be rotated in a clockwise direction about hingepin 15, relieving the pressure between the end of pin 22 and roller 33,thereby I allowing arm 3| to move to the left as viewed in Fig. l awayfrom operating pin 34 and reversing the function of micro switch 20.

It will be apparent from the following description that the location andoperation of micro switch 26 is such that no conscious effort on the'part of the operator is required to effect its operation. The operatormerely turns switch i8 to its on position and leaves it in that positionwhile going from one work station to another, the motor beingautomatically started by the micro switch and stopped by the aforesaidcontrol. The motor is reversed by the pull of the This operator onhandle Hi to withdraw the tool from the tube, which automaticallyrestores micro switch 20 to its initial condition.

Since the entire handle 16 moves to operate micro switch 20, it is notnecessary for the operator to look for and depress a special button eachtime he changes work stations. This is particularly advantageous whereunskilled labor is used.

When the handle i6 is to be removed for servicing or inspection, hingepin 15 is removed and handle 16 is then rotated approximately 90 aboutpin 22 until lugs 35 clear stops 36, whereupon the handle is pulled tothe right as viewed in Fig. 2;

It is understood that the foregoing description is illustrative of apreferred embodiment of this invention and that the scope of theinvention is not to be limited thereto, but is to be determined by theappended claims.

What is claimed is:

1. In a portable electric tool having a casing and a motor therein, asubstantially U-shaped grip, a hinged connection between the casing andone leg of the U, a guide pin on the casing, the other leg having anopening therein aligned with the pin, a motor-controlling switch in thegrip having an operating lever aligned with the pin and adapted to beoperated by the pin as the grip is rotated in one direction about thesaid hinged connection, resilient means interposed between the saidother leg and the casing and urging the grip in one direction, and stopmeans on the casing cooperating with the grip and limiting the movementof the grip relative to the housing to an oscillatory movement.

2. In a tool having a casing, a substantially U-shaped grip, a separablepivoted connection between the casing and one leg of the U, a guide pinon the casing, the other leg having an opening therein aligned with thepin, a tool-control means in the grip, said-means having an operatinglever aligned with the pin and adapted to be operated by the pin as thegrip is rotated in one direction about said pivoted connection. anabutment on the said other leg, and a stop on the pin adapted to strikesaid abutment to limit movement of the handle relative to said pin, saidabutment being movable out of the path of the stop when the said pivotedconnection is separated and the grip is rotated about the said pin.

3. In a tool, the combination as described in claim 2, said openingbeing of substantially the same contour as the stop such that when thegrip is rotated about the pin, the stop will become aligned with theopening and will pass through the opening, thereby permitting aseparation between the grip and, tool.

NEWELL BRACKETT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 756,357 Gunnell Apr. 5, 19041,546,474 Connell July 21, 1925 1,596,013 Gebhardt Aug. 17, 19261,719,143 Slater July 2, 1929 1,751,781 Weiss Mar. 25, 1930 2,237,646Wilhide Apr. 8, 1941 2,339,087 Mantz Jan. 11, 1944

